JPH1048883A - Colored fine particles, their production and electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain colored fine particles excellent in dispersibility and stability of a charged state through simplified producing processes. SOLUTION: When a polymerizable monomer compsn. prepd. by dispersing a colorant in at least a polymerizable monomer is suspended in an aq. dispersive medium and polymerized to obtain colored fine particles, the colorant is dispersed in the polymerizable monomer in the presence of a dispersant, the viscosity of the polymerizable monomer compsn. is regulated to <=300cP and the viscosity of the compsn. after suspension in the aq. dispersive medium is regulated to <=100cP.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to colored fine particles, an electrophotographic toner using the same, and a method for producing the same. In particular, the present invention relates to a colored fine particle having excellent dispersibility and charge stability. The present invention relates to an electrophotographic toner and a method for producing the same.

[0002]

2. Description of the Related Art Colored fine particles obtained by dispersing and blending various pigments represented by carbon black into various resin materials are widely used, for example, as raw materials for electrophotographic toners.

[0003] As a method for producing such colored fine particles, a pigment component is mixed with a resin material, melt-kneaded and then pulverized to obtain colored fine particles, or a pigment component is dispersed and compounded in a polymerizable monomer. A suspension polymerization method for producing colored fine particles by performing suspension polymerization in an aqueous medium is known.

[0004] Among them, the suspension polymerization method has been widely used in recent years because fine particles having a relatively uniform particle size distribution and a spherical shape can be obtained.

However, many colorants such as carbon black have a weaker affinity for other substances, for example, water, organic solvents or organic polymers, than the cohesive force between particles, resulting in secondary agglomeration. Cheap. Therefore, when performing the above-mentioned suspension polymerization, a problem is how to uniformly disperse the colorant.

JP-A-60-254050 discloses the addition of a phenol / terpene copolymer for the purpose of improving the stability of suspension polymerization when additives such as carbon black and a charge control agent are added. A method is disclosed.

Japanese Patent Application Laid-Open No. 7-199536 discloses that
A monomer or polymer having a polar functional group in the oil phase,
In particular, a method is disclosed in which the dispersibility of a colorant is improved by adding a monomer and a polymer of sodium styrene sulfonate and p-carboxystyrene. Further, in Examples disclosed in the publication, a very small amount of an anionic surfactant (sodium dodecylbenzenesulfonate) and tricalcium phosphate are used as a suspension dispersion stabilizer.

[0008]

If the dispersion stability of the colorant in the polymerizable monomer composition is insufficient, the colorant aggregates and the viscosity increases. If the viscosity of the polymerizable monomer composition is high and the suspension of the polymerizable monomer composition is suspended in an aqueous dispersion medium by a conventionally known method, the droplets of the polymerizable monomer composition are difficult to be miniaturized, and coarse particles of 10 μm or more are generated. . Coarse droplet particles in suspension have low stability, and coalescence of particles occurs during polymerization,
This causes adhesion to the stirring blades and the polymerization vessel, so that stable and high-yield polymerization cannot be performed.

For this reason, Japanese Patent Laid-Open Publication No.
It has been necessary to reduce the size of coarse particles by making the polymerizable monomer composition droplets fine by a specific method as disclosed in Japanese Patent No. 9536 or a method of performing a suspension treatment by stirring for a long time.

If the dispersion stability of the colorant in the polymerizable monomer composition is insufficient, the colorant transfers to the aqueous phase during suspension in an aqueous dispersion medium and during polymerization, resulting in a decrease in coloring power. This causes problems such as loss of raw materials, contamination of colored fine particles by the free colorant transferred to the aqueous phase, and contamination of wastewater. In particular, it was remarkable in the case of a coloring agent having a hydrophilic group such as carbon black.

When hydrophilic inorganic fine particles such as hardly soluble inorganic salts are used as a suspension dispersion stabilizer, the viscosity of the suspension increases due to the structural viscosity of these fine particles formed in an aqueous phase, and the liquid exhibits thixotropic properties. This phenomenon tends to increase with increasing temperature. Although a small amount of surfactant is used in combination for the purpose of preventing this, it is not a definitive measure.

For this reason, it is necessary to increase the stirring power in order to make the stirring during the polymerization uniform and eliminate the variation in the temperature distribution. However, increasing the stirring force causes the particles in the suspension to coalesce and become coarse, and thus impairs the polymerization stability.

Further, in order to remove the above suspension / dispersion stabilizer, an operation such as an acid treatment is required after the polymerization, and a complicated washing operation is required.

The polymer dispersion stabilizer has a small increase in the viscosity of the suspension as in the case of using the above-mentioned hardly soluble inorganic salt and inorganic fine particles, but the dispersion stability of the colorant in the polymerizable monomer composition. In the case where the colorant has a low tendency to transfer to the aqueous phase side, the viscosity of the suspension increases.

This tendency becomes more pronounced when the content, that is, the concentration, of the polymerizable monomer composition in the suspension is increased.
It was difficult to increase the concentration and increase the production efficiency.

Further, since the polymer dispersion stabilizer is difficult to wash and remains on the surface of the colored fine particles, when the colored fine particles are used as a toner, they cause a decrease in fluidity and environmental stability. I have.

Accordingly, an object of the present invention is to provide colored fine particles having improved properties, an electrophotographic toner using the same, and a method for producing the same.
The present invention provides colored fine particles having particularly excellent dispersibility and charge stability, an electrophotographic toner using the same, and a method for producing the same.

[0018]

The above objects can be achieved by (1) suspending and polymerizing a polymerizable monomer composition obtained by dispersing a coloring agent in at least a polymerizable monomer in an aqueous dispersion medium. In the colored fine particles, the colorant is dispersed in the polymerizable monomer in the presence of the dispersant, and the viscosity of the polymerizable monomer composition becomes 3
It is achieved by colored fine particles, which are obtained when the viscosity is 100 cP or less and the viscosity when the polymerizable monomer composition is suspended in an aqueous dispersion medium is 100 cP or less.

The present invention also provides (2) a dispersant for dispersing a colorant in a polymerizable monomer, wherein the dispersant is a rosin derivative, an aromatic petroleum resin, a pinene resin, an epoxy resin, a cumarone resin, and styrene- The colored fine particles according to the above (1), which are at least one resin selected from the group consisting of acrylic resins.

The above-mentioned objects are also achieved by (3) a method in which a polymerizable monomer composition comprising at least a polymerizable monomer and a colorant dispersed therein is suspended in an aqueous dispersion medium and polymerized. The colorant is dispersed in the polymerizable monomer in the presence of the dispersant, the viscosity of the polymerizable monomer composition is 300 cP or less, and the polymerizable monomer composition is suspended in an aqueous dispersion medium. The viscosity can be attained by a method for producing colored fine particles, wherein the viscosity is 100 cP or less.

In the present invention, (4) the dispersant for dispersing the colorant in the polymerizable monomer may be a rosin derivative, an aromatic petroleum resin, a pinene resin, an epoxy resin, a cumarone resin, (3) The method for producing colored fine particles according to (3), wherein the resin is at least one resin selected from the group consisting of acrylic resins.

The above objects can also be attained by an electrophotographic toner comprising the colored fine particles according to any one of the above (1) and (2).

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments. In the present invention, colored fine particles are produced by suspending and polymerizing a polymerizable monomer composition obtained by dispersing a colorant in a polymerizable monomer that forms a binder resin by polymerization in an aqueous dispersion medium. In this case, first, the colorant is dispersed in the polymerizable monomer in the presence of a dispersant. When the colorant is dispersed in the presence of the dispersant as described above, the dispersibility of the colorant in the polymerizable monomer composition is improved, and the viscosity of the polymerizable monomer composition is reduced. In the present invention, the viscosity is 300 cP or less, more preferably 250 cP or less, and further preferably 200 to 1 cP.
It is characterized by being.

Since the viscosity of the polymerizable monomer composition is low, a special method may be adopted in the suspension polymerization, or the suspension treatment by stirring may not be performed under a high shear force for a long time. In both cases, a droplet having a desired particle size can be obtained in a short time by a suspension method generally used by those skilled in the art, and the possibility of generation of coarse particles is extremely small. Further, since the dispersibility of the colorant in the polymerizable monomer composition is good, migration of the colorant to the aqueous phase side is small.

Further, the viscosity of the suspension in which such a polymerizable monomer composition is suspended also becomes low.
P or less, more preferably 80 cP or less, and even more preferably 50 to 1 cP, so that uniform mixing can be performed by gentle stirring during polymerization, and no coarse particles are generated.
The polymerization stability is very good and the yield is high.

As a result, the dispersion of the colorant in the obtained colored fine particles is uniform, and the uniformity of the content of the colorant among the colored fine particles is also increased. Further, problems in production such as environmental pollution and increase in raw material cost due to the transfer of the coloring agent in the aqueous medium can be solved.

Further, since the viscosity of the polymerizable monomer composition is low as described above, the polymerization can be stably completed even if only a surfactant is used as a suspension / dispersion stabilizer. When only a surfactant is used as a suspension dispersion stabilizer, a polymer stabilizer such as polyvinyl alcohol and a hardly soluble inorganic salt such as calcium phosphate, which have been conventionally used as a suspension dispersion stabilizer, are used. It is required that the dispersibility and dispersion stability of the colorant in the polymerizable monomer be higher than in the case where the surfactant is only used in a system having poor dispersibility and dispersion stability. When used as a turbid dispersion stabilizer, the dispersion stability of droplets of the polymerizable monomer composition (oil phase) during suspension polymerization is reduced, and aggregation and adhesion to a polymerization vessel, stirring blades, and the like occur. As a result, a problem occurs. However, in the present invention, the dispersion stability of the colorant in the polymerizable monomer is extremely good by dispersing the colorant in the polymerizable monomer in the presence of the dispersant as described above. It becomes something
Since the viscosity is low, even if only the surfactant is used as the suspension / dispersion stabilizer, such a problem does not occur. Since only a surfactant is used as the suspension dispersion stabilizer, the dispersion stabilizer is dissolved with an acid or alkali after the polymerization reaction is completed, as in the case of using a hardly soluble inorganic salt or the like. This eliminates the need to perform a complicated operation such as repeating the operation several times, thereby simplifying the manufacturing process.

The polymerizable monomer used in the method for producing colored fine particles of the present invention is not particularly limited as long as it is capable of suspension polymerization, and is generally used in the field of toner. Various vinyl monomers, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-
Styrene monomers such as methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrenestyrene, α-methylstyrene; methyl acrylate, ethyl acrylate N-butyl acrylate, isobutyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate,
(Meth) acrylic ester monomers such as stearyl methacrylate; olefin resins such as ethylene, propylene and butylene, and others, acrylic acid, methacrylic acid,
Vinyl chloride, vinyl acetate, acrylonitrile, acrylamide, methacrylamide, N-vinylpyrrolidone and the like can be used alone or in combination of two or more. Among these, those containing a styrene monomer and / or a (meth) acrylate monomer as a main component are preferable. Further, the formation of a styrene- (meth) acrylate-based copolymer using a styrene-based monomer and a (meth) acrylate-based monomer is advantageous in terms of low-temperature fixability and storage stability. Desirably, styrene is used in an amount of 5 from the viewpoint of thermal characteristics of a toner using the obtained binder resin.
A styrene- (meth) acrylate mixture containing 0% by weight or more is preferred.

When the polymerizable monomer component is subjected to suspension polymerization to obtain colored fine particles in this manner, another polymer such as polyester may be present in the monomer component. Known additives such as a chain transfer agent for adjusting the degree may be appropriately blended. At the time of suspension polymerization, a crosslinking agent may be used.

Examples of the crosslinking agent include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene and derivatives thereof, ethylene glycol dimethacrylate,
Diethylenically unsaturated carboxylic acid esters such as diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, allyl methacrylate, t-butylaminoethyl methacrylate, tetraethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, etc. , N, N-divinylaniline, divinyl ether,
Examples include all divinyl compounds of divinyl sulfide and divinyl sulfonic acid, and compounds having three or more vinyl groups. Further, polybutadiene, polyisoprene, unsaturated polyester, chlorosulfonated polyolefin and the like are also effective.

On the other hand, the colorant dispersed in such a polymerizable monomer is a pigment or the like well known to those skilled in the art, and may be an organic pigment, an inorganic pigment, or a mixture thereof.

Examples of the inorganic pigment include carbon black, alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, and diatomaceous earth. , Various inorganic oxide pigments, chromium oxide,
Powders or particles such as cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silica fine powder, silicon carbide, silicon nitride, boron carbide, tungsten carbide, titanium carbide, cerium oxide, etc. Is mentioned.
Further, such an inorganic pigment is a titanium coupling agent,
It may have been treated with a known hydrophobizing agent such as a silane coupling agent or a higher fatty acid metal salt.

Examples of organic pigments include Navels Yellow, Naphthol Yellow S, Hanser Yellow G, Hanser Yellow 10G, Benzidine Yellow G,
Yellow pigments such as Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, etc., Kilybdenum Orange, Permanent Orange R
Orange pigments such as K, benzidine orange G, indanthrene brilliant orange GK, permanent red 4
Red pigments such as R, Risor Red, Pyrazolone Red 4R, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eomine Lake, Rhodamine Lake B, Buzarin Lake, Brilliant Carmine B, etc .; Blue pigments such as alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partial chloride, fast sky blue, and indanthrene blue BC; green pigments such as pyrakite green lake and final yellow green G; Is mentioned.

When a magnetic toner is to be obtained, for example, a magnetic powder such as a powder of a ferromagnetic metal such as iron, cobalt or nickel, or a powder of a metal compound such as magnetite, hematite or ferrite is added. It is also possible. Since these magnetic powders also act as colorants,
When a magnetic toner is to be obtained, these magnetic powders can be used alone or in combination with the pigment as a colorant.

In the present invention, the amount of the colorant in the polymerizable monomer composition is not particularly limited and depends on the type of the colorant used. Colorant 3 to 100 parts by weight of monomer
It is desirably 20 parts by weight, preferably about 5 to 15 parts by weight. That is, if the colorant is less than 3 parts by weight, the coloring degree of the obtained colored fine particles is not sufficient, while if it exceeds 20 parts by weight, the effect of increasing the addition amount is not so much seen, Further, there is a problem that the viscosity of the polymerizable monomer composition sharply increases, and further, the polymerization of the polymerizable monomer may not sufficiently proceed.

As a coloring agent, for example, a dye such as a nigrosine dye can be used in combination with the above-mentioned pigment.

In the present invention, such a colorant is dispersed in the polymerizable monomer in the presence of a dispersant (hereinafter, also referred to as “colorant dispersant”). As the dispersant, at least one resin selected from the group consisting of a rosin derivative, an aromatic petroleum resin, a pinene resin, an epoxy resin, a coumarone resin, and a styrene-acryl diameter resin is useful. In the present invention, it is important to disperse the colorant in the presence of the colorant dispersant, and adding the dispersant after the colorant dispersal has no effect.

Specific examples of the rosin derivative include rosin ester, hydrogenated rosin, hydrogenated rosin ester, dibasic acid-modified rosin, and polymerized rosin. Examples of the aromatic petroleum resin include neopolymer. 8, L-9
0, 100, 120, 130, 140, 150, 16
0, 170S (manufactured by Nippon Synthetic Resins Co., Ltd.) and the like, as pinene-based resins, for example, α-pinene resin and β-pinene resin, and as the epoxy resin, for example, room temperature (2
Bisphenol A solid or liquid at 5 ° C ± 2 ° C)
Types, halogenated bisphenol type, resorcinol type, bisphenol F type, novolak type, polyalcohol type, polyglycol type, polyolefin type, alicyclic type and the like. Further, as the coumarone resin, for example, Escron G-90 , N-100, V-120 (manufactured by Nippon Steel Chemical Co., Ltd.) and the like.
Examples of the styrene-acrylic resin include styrene, o-methylstyrene, m-methylstyrene, p-
Styrene monomers such as methyl styrene, α-methyl styrene, p-methoxy styrene, p-tert-butyl styrene, p-phenyl styrene, α-methyl styrene, and methyl acrylate, ethyl acrylate, n-acrylate
-Butyl, isobutyl acrylate, dodecyl acrylate, stearyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate,
Isobutyl methacrylate, n-octyl methacrylate,
It contains (meth) acrylate monomers such as dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, and glycidyl methacrylate as main components, and contains one or two or more of them in combination. Olefin resins such as propylene, butylene, etc., and those having other polymerizable monomers as needed, such as vinyl chloride, vinyl acetate, acrylamide, methacrylamide, and the like. However, the present invention is not limited to these.

As these colorant dispersants, rosin derivatives having an acid value of 5 to 100 KOH mg / g, a weight average molecular weight of 10,000 or less and a softening temperature of 70 ° C. to 170
C. aromatic petroleum resin, α-pinene resin, epoxy resin having a softening point of 60 ° C. to 150 ° C., cumarone resin,
And a molecular weight of 100,000 at a softening point temperature of 60 to 150 ° C.
It is desirable that the resin is at least one resin selected from the group consisting of the following styrene-acrylic resins.

In the present invention, the colorant dispersant as described above is dissolved or dispersed in the polymerizable monomer in advance, and then the colorant is added to the polymerizable monomer, or the colorant dispersant is colored. The coloring agent is added at the same time, and then the colorant is dispersed using a suitable stirring device or the like. If the colorant dispersant has poor solubility in the polymerizable monomer and is solid at room temperature, the dispersant is melted in order to uniformly disperse the polymerizable monomer. It is necessary to raise the temperature to a temperature at which the polymerizable monomer can be dissolved, and even if the polymerizable monomer has solubility, it can be heated to promote the dissolution.

The amount of such a colorant dispersant to be added cannot be specified unconditionally because it depends on the type and amount of the colorant used and the type of the dispersant used. 1 to 50 parts by weight, more preferably 2 to 3 parts by weight, based on 100 parts by weight of the reactive monomer composition
About 0 parts by weight is appropriate. That is, the colorant dispersant 1
If the amount is less than parts by weight, the viscosity of the polymerizable monomer composition is 300 c.
P, the dispersion stability of the colorant is improved by its addition,
In addition, the effect of preventing the transfer of the colorant to the aqueous phase during suspension and during the polymerization process cannot be sufficiently expected, and if it exceeds 50 parts by weight, the effect is significantly improved even if the added amount is increased. This is because the colorant dispersant is relatively low-molecular and has a high risk of lowering the printing durability after printing.

The apparatus for dispersing the colorant in the polymerizable monomer in the presence of such a dispersant is not particularly limited, but examples thereof include a ball mill, an attritor, and a sand mill. Preferred examples thereof include a shear type dispersion device such as a media type dispersion device, a homomixer, a homogenizer, and a biomixer, and an ultrasonic dispersion device.

The polymerizable monomer composition may contain an anti-offset agent, a charge control agent and the like, if necessary. The offset inhibitor added to the polymerizable monomer composition as necessary is not particularly limited, but a polymer having a cyclic method softening point of 80 to 180 ° C,
For example, a polyolefin having a weight average molecular weight of 1,000 to 45,000, more preferably about 2,000 to 6,000, that is, a so-called polyolefin wax can be used. For example, as polyolefin wax, polyethylene,
Homopolymers such as polypropylene and polybutylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-pentene copolymer, ethylene-3-methyl-1-butene copolymer, ethylene-propylene-butene copolymer Olefin copolymers such as coalescence, or olefins and other monomers, for example, vinyl methyl ether, vinyl-n-butyl ether, vinyl ethers such as vinyl phenyl ether, vinyl acetate, vinyl esters such as vinyl butyrate, Haloolefins such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, vinyl chloride, vinylidene chloride, tetrachloroethylene, methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, n (Meth) acrylates such as butyl methacrylate, stearyl methacrylate, N, N-dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, acrylic acid derivatives such as acrylonitrile, N, N-dimethylacrylamide, and acrylic Acid, methacrylic acid, maleic acid,
Examples thereof include organic acids such as fumaric acid and itaconic acid, and copolymers with diethyl fumarate, β-pinene, and the like.

As the anti-offset agent, in addition to the above-mentioned polyolefins, natural or synthetic paraffin waxes, especially high-melting paraffin wax having a melting point of 60 to 70 ° C., zinc salt of stearic acid, barium salt, lead Salts, cobalt salts, calcium salts and magnesium salts and magnesium salts. Fatty acid metal salts such as zinc, manganese, iron and lead salts of olefinic acids and zinc, cobalt and magnesium salts of palmitic acid,
Particularly, higher fatty acid salts having 17 or more carbon atoms, similarly higher alcohols such as myricyl alcohol, polyhydric alcohol esters such as glyceride stearate and glyceryl palmitate, fatty acid esters such as myristyl stearate and myristyl palmitate And partially saponified fatty acids such as partially saponified montanic acid esters, higher fatty acids such as stearic acid, palmitic acid and montanic acid, fatty acid amides such as ethylenebisstearoylamide, and mixtures thereof.

Examples of charge control agents include nigrosine, monoazo dyes, zinc, hexadecyl succinate, alkyl esters or alkylamides of naphthoic acid, nitrohumic acid, N, N-tetramethyldiaminebenzophenone, N, N-tetra Examples include methylbenzidine, triazine, and a metal salicylate complex. Incidentally, such a charge control agent, rather than added during suspension polymerization,
It is preferable that the resin be externally added to the resin particles obtained after the suspension polymerization.

In the present invention, as described above, a colorant is dispersed in a polymerizable monomer in the presence of a dispersant, and a viscosity of at least 3 including the polymerizable monomer and the colorant is obtained.
Next, a polymerizable monomer composition having a viscosity of 100 cP or less is added and suspended in an aqueous dispersion medium, and suspension polymerization is carried out at a viscosity of 100 cP or less of the suspension. As a dispersion stabilizer for stabilizing suspended particles, a surfactant is useful.

The surfactant used as the suspension / dispersion stabilizer is not particularly limited, and includes nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants. Either type may be used, and a plurality of types may be used in combination. Specifically, for example, sodium dodecylbenzenesulfonate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium allyl-alkyl-polyethersulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate , Sodium caproate, potassium stearate, calcium oleate, 3,3 '
Sodium disulfonediphenylurea-4,4'-diazo-bis-amino-8-naphthol-6-sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2 ', 5,5'-tetramethyl-tri Phenylmethane-1,1'-diazo-bis-β-naphthol-
Sodium disulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate,
Sodium alkyldiphenyl ether disulfonate,
Sodium polyoxyethylene alkyl sulfate, triethanolamine polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium alkali sulfonate, sodium salt of β-naphthalenesulfonic acid formalin condensate, special aromatic sulfonic acid formalin condensate The sodium salt of
Special carboxylic acid type polymer surfactant, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene sorbitan alkylate, lauryl Examples include trimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyldimethylammonium chloride, alkylbenzyldimethylammonium chloride, but are not limited to these.

The dispersion stabilizer comprising these surfactants is
The obtained colored fine particles have a predetermined particle size, for example, 1
１００100 μm, preferably 3-20 μm,
It should be used by appropriately adjusting its composition and amount, and is not particularly limited, but in order to obtain the desired viscosity of the suspension as described above, for example, a polymerizable monomer 0.01 to 5% by weight, preferably 0.05 to
Preferably, it is 3% by weight.

As the polymerization initiator used for the polymerization, oil-soluble peroxide-based or azo-based initiators usually used for suspension polymerization can be used. By way of example, for example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide,
Peroxide initiators such as diisopropylperoxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl hydroperoxide, diisopropylbenzene hydroperoxide, 2,2′-azobisisobutyronitrile, 2 '
Azobis (2,4-dimethylvaleronitrile), 2,
2'-azobis (2,3-dimethylbutyronitrile),
2,2′-azobis (2-methylbutyronitrile),
2,2′-azobis (2,3,3-toazobis (2-methylbutyronitrile), 2,2′-azobis (2,3
3-trimethylbutyronitrile), 2,2'-azobis (2-isopropylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2
'-Azobis (4-methoxy-2,4-dimethylvaleronitrile), 2- (carbamoylazo) isobutyronitrile, 4,4'-azobis (4-cyanovaleric acid),
Dimethyl-2,2'-azobisisobutyrate and the like. The polymerization initiator is, with respect to the polymerizable monomer, 0.1 to
It is preferably used in an amount of 20% by weight, especially 1 to 10% by weight.

In the suspension polymerization, a polymerizable monomer composition prepared by dispersing a colorant in a polymerizable monomer in the presence of a colorant dispersant as described above is used to prepare a surfactant. Suspended in an aqueous dispersion medium obtained by adding a predetermined amount of a suspension dispersion stabilizer,
For example, it is carried out at a temperature of 50 to 90 ° C, preferably 60 to 80 ° C. After the suspension polymerization is completed, the obtained colored fine particles are separated from the aqueous dispersion medium, dried, and, if necessary, subjected to a classification step to obtain a desired particle diameter, for example, an average particle diameter of 1.
Colored fine particles of about 100 μm, more preferably about 3 to 20 μm can be obtained.

The dispersion of the colorant in the colored fine particles according to the present invention thus obtained is extremely good, and the uniformity among the fine particles is also high. Further, by using the dispersant as described above, since the transfer of the colorant from the polymerizable monomer composition to the aqueous phase during suspension and polymerization is suppressed low, the colorant in the obtained colored fine particles Is the amount of the coloring agent in the polymerizable monomer composition (the amount charged), the residual ratio,
For example, it is very high such as 70% or more.

In addition, the stability at the time of polymerization is good, the yield of colored fine particles is good at 90% or more, and there is almost no contamination of the polymerization vessel, and continuous use is possible without requiring any special washing operation. It is. This is a very useful method in industrialization.

In the electrophotographic toner according to the present invention, the colored fine particles obtained as described above may be used as they are or, if necessary, with a usual charge controlling agent for adjusting the charge, a fluidizing agent or the like. It can be obtained by performing a process such as appropriately externally adding an additive commonly used in an electrostatic charge developing toner.

As the fluidizing agent, for example, inorganic fine particles such as colloidal silica, hydrophobic silica, hydrophobic titania, hydrophobic zirconia, and talc, and organic fine particles such as polystyrene beads and (meth) acrylic resin beads are used. Can be

The thus obtained electrophotographic toner has an average particle size of, for example, about 2 to 20 μm, preferably about 3.5 to 15 μm, and a sufficient amount of colorant is contained in each toner particle. When the toner is used to form an image, the resulting image has a sufficient degree of coloration because the toner is uniformly dispersed with a high content and the colorant content among the toner particles is uniform. In addition, the toner has a blackening degree and a uniform charge amount between toner particles, so that a stable image without fogging or the like can be obtained.

[0056]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In the following, "part" means "part by weight" and "%" means "% by weight" unless otherwise specified.

The viscosity, the particle diameter, the weight% of the particles having a particle size of 10 μm or more, and the yield of the colored fine particles were measured by the following methods.

Measurement of Viscosity The polymerizable monomer composition and the suspension were mixed with a B-type viscometer (Visc).
meter Model BM, TOKIMEC I
NC). In the measurement, the sample was kept at 25 ° C., and the viscosity was defined as a value of one minute after the start of the measurement at a rotation speed of 60 rpm.

The particle diameter and the weight of the particles of 10 μm or more
% Of the sample was diluted and measured with Coulter Matil Cider II (manufactured by Coulter) to obtain the respective values.

-Yield of colored fine particles obtained by polymerization After removing aggregates and the like from the polymer solution with 200 mesh, the solid content was measured, and the amount of the suspension dispersion stabilizer (theoretical value) was removed. The weight was calculated and the yield was calculated from the theoretical value. Yields are given in% by weight.

Example 1 255 parts of styrene, 45 parts of n-butyl acrylate, 0.9 part of divinylbenzene, 30 parts of carbon black (MA-100 manufactured by Mitsubishi Chemical Corporation), maleic acid-modified rosin (Luisol) as a dispersant 28-JA (oxidation 37),
A polymerizable monomer composition was prepared using 30 parts of Rika Hercules Co., Ltd., 3 parts of ABNR (manufactured by Nippon Hydrazine Industry Co., Ltd.), and 6 parts of ABNV (manufactured by Nippon Hydrazine Industry Co., Ltd.).

The dispersant (maleic acid-modified rosin) of the polymerizable monomer composition is dissolved in styrene in advance,
The mixture was placed in a 450 ml mayonnaise bottle together with 130 parts of 2.5 mm glass beads and dispersed and mixed for 30 minutes using a paint shaker. As a result of observing this polymerizable monomer composition dispersion mixture with an optical microscope, it was confirmed that carbon black was uniformly finely dispersed and that there were no coarse particles of 1 μm or more.
The viscosity of this polymerizable monomer composition was 125 cP.

The polymerizable monomer composition dispersion mixture was poured into 480 parts of a 0.2% aqueous solution of hytenol NO8 (polyoxyethylene alkyl phenyl ether sulfate ammonium, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) prepared in advance. ,
10,000 using a homomixer (manufactured by Tokushu Kika Co., Ltd.)
The mixture was stirred at rpm for 15 seconds to obtain a suspension. As a result of observing this suspension with an optical microscope, individual particles were uniformly colored black, and no uncolored transparent particles were found.

The concentration of the polymerizable monomer composition in this suspension was 42.5%, but the viscosity of the suspension was 75 cP
Met. The weight% of the particles having a size of 10 μm or more is 1.2%.
Met.

The suspension was heated under a nitrogen atmosphere while uniformly stirring the whole to such an extent that the polymer particles did not settle.
Polymerization was performed at 8 ° C. for 8 hours. The polymerization was completed very stably without adhesion to the glass separable flask and stirring blade used in the polymerization and without aggregation. The volume average particle size of the particles in this polymerization liquid was 5.3 μm, and the weight% of the particles having a size of 10 μm or more was 1.1%. The yield of the colored fine particles was 98%.

Next, the mixture was cooled to room temperature, and solid-liquid separation and washing were repeatedly performed, followed by drying with a hot air drier at 60 ° C. for 24 hours to obtain colored fine particles (1) of the present invention. The solid-liquid separated filtrate was not colored by carbon black.

The colored fine particles (1) were used as an electrophotographic toner (1), and were added to hydrophobic silica (Aerosil®).
-972, manufactured by Nippon Aerosil Co., Ltd.) and mixed well, then adjusted to a toner concentration of 4% using a styrene acrylic resin-coated ferrite carrier, and mixed to form a two-component developer. did. The developer was set on a Rheodry 7610 (manufactured by Toshiba Corporation) and a copying test was carried out. As a result, a satisfactory image having a sufficient degree of blackening and having no fog was obtained.

As a result of observing the dispersion state of the carbon black in the colored fine particles (1) with a TEM photograph, it was confirmed that the particles were uniformly finely dispersed in the particles.

Example 2 850 parts of styrene, 150 parts of n-butyl acrylate,
3 parts of divinylbenzene, 80 parts of carbon black (manufactured by Mitsubishi Chemical Corporation, # 44), aromatic petroleum resin as a dispersant (Neopolymer 100, manufactured by Nippon Synthetic Resins Co., Ltd.)
40 parts, ABNR (manufactured by Nippon Hydrazine Industry Co., Ltd.) 20
Section and ABNV (manufactured by Nippon Hydrazine Industry Co., Ltd.) 4
Using 0 parts, a polymerization monomer composition was prepared.

The dispersant (aromatic petroleum resin) of the polymerizable monomer composition is dissolved in styrene in advance and then DYN
O-MILL KDL (Willy A. Bacho
fen AG Maschinenfabrik)
Was dispersed. As a result of observing the polymerizable monomer composition dispersion mixture with an optical microscope, it was confirmed that carbon black was finely dispersed uniformly and that there were no coarse particles. Also,
The viscosity of this polymerizable monomer composition was 200 cP.

2500 parts of this polymerizable monomer composition dispersion was mixed with 0.25% of Neugen EA1 prepared in advance.
50 (polyoxyethylene alkyl phenyl ether,
The solution was poured into 450O parts of water (Daiichi Kogyo Seiyaku Co., Ltd.) and passed once at 15000 rpm with Ebara Milder (Ebara Corporation) to obtain a suspension.

As a result of observing this suspension with an optical microscope,
Individual particles were uniformly colored black, and no uncolored transparent particles were found.

Although the concentration of the polymerizable monomer composition in this suspension was 26.3%, the viscosity of the suspension was 13 cP
Met. The weight% of the particles having a size of 10 μm or more is 3.0%.
Met.

The suspension was heated under a nitrogen atmosphere while uniformly stirring the whole to such an extent that the polymer particles did not settle.
Polymerization was carried out at 6 ° C. for 6 hours. As in Example 1, the polymerization was completed stably without adhesion or aggregation.

The particle size of the polymerization solution was measured with a Coulter Multisider II (manufactured by Coulter Inc.). As a result, the weight average particle size was 6.8 μm, and the weight% of particles having a size of 10 μm or more was 2.8%. The yield of the colored fine particles was 95%.

Then, the mixture was cooled to room temperature, and solid-liquid separation and washing were repeatedly performed, followed by drying with a hot air drier at 60 ° C. for 24 hours to obtain colored fine particles (2) of the present invention. The solid-liquid separated filtrate was not colored by carbon black.

The colored fine particles (2) were used as an electrophotographic toner (2), and were added with hydrophobic silica (Aerosil®).
-972, manufactured by Nippon Aerosil Co., Ltd.) and mixed well, then adjusted to a toner concentration of 4% using a styrene acrylic resin-coated ferrite carrier, and mixed to form a two-component developer. did.

This developer was set on Rheodry 7610 (manufactured by Toshiba Corporation), and a copying test was carried out. As a result, a satisfactory image having a sufficient degree of blackening and having no fog was obtained.

The state of dispersion of the carbon black in the colored fine particles (2) was observed with a TEM photograph, and it was confirmed that the particles were uniformly finely dispersed in the particles.

Example 3 The dispersant for the polymerizable monomer composition of Example 2 was changed to α-pinene resin (YS Resin A # 800, manufactured by Yashara Chemical Co., Ltd.).
Except that the amount was 120 g, a polymerizable monomer composition (3) was obtained in exactly the same manner as in Example 2.

The polymerizable monomer composition (3) after the dispersion treatment was evaluated in the same manner as in Example 1. As a result, it was confirmed that carbon black was finely dispersed uniformly and no coarse particles were present. The viscosity of the polymerizable monomer composition is 250 cP.
Met.

Using this polymerizable monomer composition dispersion, a suspension was obtained in the same manner as in Example 2. As a result of observing this suspension with an optical microscope, individual particles were uniformly colored black, and no uncolored transparent particles were found.

Although the concentration of the polymerizable monomer composition in this suspension was 27.8%, the viscosity of the suspension was 20 cP
Met. The weight% of the particles having a size of 10 μm or more is 5.0%.
Met.

Using this suspension, polymerization was carried out in the same manner as in Example 2. The polymerization stability was good as in Example 2. The weight average particle diameter of the colored fine particles (3) is 7.3 μm.
In m, the weight percent of particles greater than 10 μm was 5.2%. The yield of the colored fine particles was 96%.

The filtrate separated from solid and liquid was not colored by carbon black. The dispersion state of carbon black in the particles of the colored fine particles (3) was also evaluated in the same manner as in Example 1. As a result, it was confirmed that the particles were uniformly dispersed in the particles.

The colored fine particles (3) were used as an electrophotographic toner (3), and were added to hydrophobic silica (Aerosil®).
-972, manufactured by Nippon Aerosil Co., Ltd.) and mixed well, then adjusted to a toner concentration of 4% using a styrene acrylic resin-coated ferrite carrier, and mixed to form a two-component developer. did.

An image forming test was performed on this developer in the same manner as in Example 1. As a result, a good image having a sufficient degree of blackening and having no fog was obtained.

Example 4 The dispersant in the polymerizable monomer composition of Example 1 was changed to a cumarone resin (Escron N-100S, Nippon Steel Chemical Co., Ltd.).
The polymerizable monomer composition (4) was obtained in exactly the same manner as in Example 1 except that the amount was 60 parts. As a result of evaluating the polymerizable monomer composition after the dispersion treatment in the same manner as in Example 1, it was confirmed that carbon black was finely dispersed uniformly and that there were no coarse particles. The polymerizable monomer composition has a viscosity of 1
It was 81 cP.

Using this polymerizable monomer composition dispersion, a suspension was obtained in the same manner as in Example 1. As a result of observing this suspension with an optical microscope, individual particles were uniformly colored black, and no uncolored transparent particles were found.

The concentration of the polymerizable monomer composition in this suspension was 44.4%, and the viscosity of the suspension was 11 cP
Met. The weight% of the particles having a size of 10 μm or more is 2.3%.
Met.

Using this suspension, polymerization was carried out in the same manner as in Example 1. The polymerization stability was also good as in Example 1. The weight average particle diameter of the colored fine particles (4) is 5.9 μm.
m, the weight percent of particles greater than 10 μm was 2.5%. The yield of the colored fine particles was 97%.

[0092] The solid-liquid separated filtrate was not colored by carbon black. The dispersion state of carbon black in the particles of the colored fine particles (4) was also evaluated in the same manner as in Example 1. As a result, it was confirmed that the particles were uniformly dispersed in the particles.

The colored fine particles (4) were used as an electrophotographic toner (4), and were added with hydrophobic silica (Aerosil®).
After adding 0.8% of -972 Nippon Aerosil Co., Ltd.) and mixing well, a styrene acrylic resin-coated ferrite carrier was used to adjust the toner concentration to 4% and mixed to prepare a two-component developer. . The developer was set on a Rheodry 7610 (manufactured by Toshiba Corporation) and a copying test was carried out. As a result, a satisfactory image having a sufficient degree of blackening and having no fog was obtained.

Example 5 80 parts of an epoxy resin (Epicoat 1002, manufactured by Yuka Shell Epoxy Co., Ltd., softening temperature (ring and ball method) of 78 ° C.) was used as a dispersant in the polymerizable monomer composition of Example 1, and carbon black was used. Was changed to 20 parts, and a polymerizable monomer composition (5) was obtained in exactly the same manner as in Example 1. As a result of evaluating the polymerizable monomer composition after the dispersion treatment in the same manner as in Example 1, it was confirmed that carbon black was finely dispersed uniformly and that there were no coarse particles. The viscosity of the polymerizable monomer composition was 103 cP.

Using this polymerizable monomer composition dispersion, a suspension was obtained in the same manner as in Example 1 except that 480 parts of the 0.2% hytenol N08 aqueous solution of Example 1 was changed to 950 parts. .

As a result of observing this suspension with an optical microscope,
Individual particles were uniformly colored black, and no uncolored transparent particles were found.

Although the concentration of the polymerizable monomer composition in this suspension was 29.5%, the viscosity of the suspension was 6.2 c.
P. The weight% of the particles having a size of 10 μm or more is 5.0.
%Met.

Using this suspension, polymerization was carried out in the same manner as in Example 1. The polymerization stability was also good as in Example 1. The weight average particle diameter of the colored fine particles (5) is 6.3 μm.
In m, the weight percent of particles greater than 10 μm was 5.2%. The yield of the colored fine particles was 98%.

[0099] The solid-liquid separated filtrate was not colored by carbon black. The dispersion state of carbon black in the particles of the colored fine particles (5) was also evaluated in the same manner as in Example 1. As a result, it was confirmed that the particles were uniformly dispersed in the particles.

The colored fine particles (5) were used as an electrophotographic toner (5), and were added with hydrophobic silica (Aerosil®).
-972, manufactured by Nippon Aerosil Co., Ltd.) and mixed well, then adjusted to a toner concentration of 4% using a styrene acrylic resin-coated ferrite carrier, and mixed to form a two-component developer. did. The developer was set on a Rheodry 7610 (manufactured by Toshiba Corporation) and a copying test was carried out. As a result, a satisfactory image having a sufficient degree of blackening and having no fog was obtained.

Example 6 Example 6 was repeated except that the dispersant in the polymerizable monomer composition of Example 5 was changed to styrene-acrylic resin (styrene / glycidyl methacrylate = 95/5 (weight ratio), Mw = 15000). Polymerizable monomer composition (6) was obtained in exactly the same manner as in (5).

The polymerizable monomer composition after the dispersion treatment was evaluated in the same manner as in Example 1. As a result, it was confirmed that carbon black was finely dispersed uniformly and no coarse particles were present. The viscosity of this polymerizable monomer composition was 155 cP.

Using this polymerizable monomer composition dispersion, a suspension was obtained in the same manner as in Example 5. As a result of observing this suspension with an optical microscope, individual particles were uniformly colored black, and no uncolored transparent particles were found.

The concentration of the polymerizable monomer composition in this suspension was 29.5%, and the viscosity of the suspension was 15 cP
Met. The weight% of the particles having a size of 10 μm or more is 3.8%.
Met.

Using this suspension, polymerization was carried out in the same manner as in Example 5. The polymerization stability was also good as in Example 1. The weight average particle diameter of the colored fine particles (6) is 6.8 μm.
m, the weight percent of particles greater than 10 μm was 3.5%. The yield of the colored fine particles was 96%.

The filtrate separated from solid and liquid was not colored by carbon black. The dispersion state of carbon black in the particles of the colored fine particles (6) was also evaluated in the same manner as in Example 1. As a result, it was confirmed that the particles were uniformly dispersed in the particles.

The colored fine particles (6) were used as an electrophotographic toner (6), and were added with hydrophobic silica (Aerosil®).
-972, manufactured by Nippon Aerosil Co., Ltd.) and mixed well, then adjusted to a toner concentration of 4% using a styrene acrylic resin-coated ferrite carrier, and mixed to form a two-component developer. did. The developer was set on a Rheodry 7610 (manufactured by Toshiba Corporation) and a copying test was carried out. As a result, a satisfactory image having a sufficient degree of blackening and having no fog was obtained.

Comparative Example 1 Comparative polymerizable monomer composition (1) was obtained in the same composition and operation as in Example 1 except that the dispersant for the polymerizable monomer composition of Example 1 was not added. Was.

The polymerizable monomer composition after the dispersion treatment was evaluated in the same manner as in Example 1.

As a result of observing the dispersion state of carbon black in the dispersion mixture of the polymerizable monomer composition with an optical microscope,
Dispersion of the carbon black was poor, and coarse particles of 1 μm or more were included, and secondary aggregation was immediately caused due to lack of dispersion stability. The viscosity of the polymerizable monomer composition is 4
It was 20 cP.

Using this polymerizable monomer composition dispersion, a suspension was obtained in the same manner as in Example 1. As a result of observing the suspension with an optical microscope, it was confirmed that individual particles had non-uniform blackness of the particles and transparent particles were present.

The concentration of the polymerizable monomer composition in this suspension was 40.8%, but the viscosity of the suspension was 210 c.
P, indicating thixotropic properties. In addition, the stability of the suspension is poor, and Coulter Multisider II
Was not possible.

Using this suspension, polymerization was carried out in the same manner as in Example 1. The polymerization stability of this suspension was insufficient, and considerable adhesion to the glass separable flask and stirring blades used for the polymerization was observed.

Comparative colored fine particles obtained by polymerization (1)
Had a weight average particle size of 7.5 μm, and the weight% of particles having a particle size of 10 μm or more was 15%. The yield of the obtained comparative colored fine particles (1) was 56%.

As a result of observing the dispersion of the carbon black in the particles of the comparative colored fine particles (1) by a TEM photograph, the carbon black was gathered near the particle surface and was hardly present at the particle center.

The solid-liquid separated filtrate is colored black,
Transfer of the carbon black to the aqueous phase side was observed.

A developer was prepared using the comparative colored fine particles (1) as a comparative toner (1) in the same manner as in Example 1.
As a result of a copy test, toner scattering was observed, fogging was observed on the image, and only an image having a low degree of blackening was obtained.

Comparative Example 2 A method similar to that of Example 1 was used, except that the dispersant in the polymerizable monomer composition of Example 1 was a phenol / terpene copolymer (YS Polystar S145, manufactured by Yashara Chemical Co., Ltd.). Thus, a comparative polymerizable monomer composition (2) was obtained.

Then, the polymerizable monomer composition after the dispersion treatment was evaluated in the same manner as in Example 1.

As a result of observing the dispersion state of carbon black in the dispersion mixture of the polymerizable monomer composition with an optical microscope,
Carbon black was finely dispersed and did not contain coarse particles, but was a dispersion having low dispersion stability and easily causing secondary aggregation. The viscosity of the polymerizable monomer composition is 350 cP
Met.

Using this polymerizable monomer composition dispersion, the 0.2% hytenol NO8 aqueous solution of Example 1 was mixed with water 833 containing 3% tricalcium phosphate and 0.04% sodium dodecylbenzenesulfonate. Example 1 except for the parts
A suspension was obtained in the same manner as described above. As a result of observing the suspension with an optical microscope, individual particles were not uniform in the degree of blackness of the particles, but the presence of transparent particles was not recognized.

Although the concentration of the polymerizable monomer composition in this suspension was 30%, the viscosity of the suspension was 120 cP, indicating thixotropic properties. 10 μm
The weight% of the above particles was 18.5%.

Using this suspension, polymerization was carried out in the same manner as in Example 1. The polymerization stability of this suspension was relatively good. The weight average particle diameter of the comparative colored fine particles (2) obtained by polymerization was 8.8 μm, and the weight% of particles having a particle diameter of 10 μm or more was 15.8%. The yield of the obtained comparative colored fine particles (2) was 81%. there were. As a result of observing the dispersion of the carbon black in the particles of the comparative colored fine particles (2) with a TEM photograph, the dispersion state was such that the particles were unevenly dispersed and aggregated in the particles.

The solid-liquid separated filtrate is colored black,
Transfer of the carbon black to the aqueous phase side was observed.

Using the comparative colored fine particles (2) as a comparative toner (2), a developer was prepared in the same manner as in Example 1.
As a result of a copy test, toner scattering was observed, fogging was observed on the image, and only an image having a low degree of blackening was obtained.

Comparative Example 3 A comparative polymerizable monomer composition was prepared in the same manner as in Example 1 except that the dispersant of the polymerizable monomer composition of Example 1 was changed to 9 parts of p-carboxystyrene. (3) was obtained.

Then, the polymerizable monomer composition after the dispersion treatment was evaluated in the same manner as in Example 1.

As a result of observing the dispersion state of carbon black in the dispersion mixture of the polymerizable monomer composition with an optical microscope,
Carbon black was finely dispersed and did not contain coarse particles, but was a dispersion having low dispersion stability and easily causing secondary aggregation. The viscosity of this polymerizable monomer composition is 445 cP
Met.

Using this polymerizable monomer composition dispersion, a suspension was obtained in the same manner as in Comparative Example 2. As a result of observing the suspension with an optical microscope, individual particles were not uniform in the degree of blackness of the particles, but the presence of transparent particles was not recognized.

The concentration of the polymerizable monomer composition in this suspension was 28.8%, and the viscosity of the suspension was 117 cP. The weight% of the particles having a size of 10 μm or more was 19.1%.

Using this suspension, polymerization was carried out in the same manner as in Example 1. Comparative colored fine particles obtained by polymerization (3)
Was 8.1 μm, and the weight% of particles having a particle size of 10 μm or more was 16.6%. The yield of the obtained comparative colored fine particles (3) was 73%. The dispersion of carbon black in the comparative colored fine particles (3) was determined by T
As a result of observation with an EM photograph, it was in a dispersed state in which carbon black was gathered near the particle surface.

The solid-liquid separated filtrate is colored black,
Transfer of the carbon black to the aqueous phase side was observed.

A developer was prepared in the same manner as in Example 1 using the comparative colored fine particles (3) as a comparative toner (3), and a copy test was performed. As a result, an image having a degree of blackening was obtained. , Toner scattering and fogging were observed.

[0134]

As described above, according to the present invention, at least a polymerizable monomer composition obtained by dispersing a colorant in a polymerizable monomer is suspended in an aqueous dispersion medium and polymerized to form colored fine particles. In obtaining, the colorant is dispersed in the polymerizable monomer in the presence of the dispersant, and the viscosity of the polymerizable monomer composition is 300.
cP or less, and the viscosity when the polymerizable monomer composition is suspended in an aqueous dispersion medium is characterized by being obtained by being 100 cP or less, the resulting colored fine particles in The dispersion of the coloring agent is uniform, and the uniformity of the coloring agent content among the coloring fine particles is also increased. For this reason, when such colored fine particles are used as an electrophotographic toner, the degree of coloring or blackening of the obtained image is sufficient, and there is no possibility that a problem such as image fogging will occur. It is. In addition, the polymerizable monomer composition obtained by performing the dispersion treatment of the colorant into the polymerizable monomer in the presence of the dispersant as described above is transferred to the aqueous phase during suspension in an aqueous medium and during the polymerization process. The transfer of the colorant is small, and the polymerization can be stably completed even when only the surfactant is used as the suspension / dispersion stabilizer. In addition, there is no need to provide a complicated processing step required for removing the suspension / dispersion stabilizer after completion of the polymerization, which has an advantage that the production step can be simplified.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Tatsuto Matsuda 5-8 Nishiburi-cho, Suita-shi, Osaka Nippon Shokubai Co., Ltd.

Claims (4)

[Claims] Claims: 1. A colored fine particle obtained by suspending and polymerizing a polymerizable monomer composition obtained by dispersing a colorant in at least a polymerizable monomer in an aqueous dispersion medium, and coloring the polymerizable monomer. The agent is dispersed in the presence of a dispersant, the viscosity of the polymerizable monomer composition is 300 cP or less, and the viscosity when the polymerizable monomer composition is suspended in an aqueous dispersion medium is 100 cP.
Colored fine particles obtained by being at most P. 2. A method for producing colored fine particles obtained by suspending and polymerizing a polymerizable monomer composition obtained by dispersing a colorant in at least a polymerizable monomer in an aqueous dispersion medium. The colorant is dispersed in the presence of a dispersant, the viscosity of the polymerizable monomer composition is 300 cP or less, and the viscosity when the polymerizable monomer composition is suspended in an aqueous dispersion medium. Is not more than 100 cP. 3. A dispersant for dispersing a colorant in a polymerizable monomer, the dispersant comprising a rosin derivative, an aromatic petroleum resin, a pinene resin, an epoxy resin, a cumarone resin and a styrene-acrylic resin. At least one selected from
3. The method for producing colored fine particles according to claim 2, wherein the resin is a kind of resin. 4. An electrophotographic toner containing the colored fine particles according to claim 1.